In A/C system. After sitting in sun all day, vent air comes out warm, seems to take too long to cool down. In addition, I do not seem to get any/much air from defrost outlets, even when defrost is selected. Is there any common failure that would cause these symptoms?

Thanks, Drake

Have you tried the self test for the control unit in the service manual? It should help you with any issues with the mix door actuators that could cause the defrost issues.

The slow cooling sounds more like low refrigerant. With slightly low refrigerant, it's common for the system to cool well in mild weather, but unable to keep up in hotter situations. You might also notice better cooling when the car is moving, or at idle. Of course all of this is speculation without seeing pressure numbers, but that's my experience.

+1 for let's see the system pressures along with ambient temp/relative humidity.

I'll check my FSM for the self check. I do not have consult, if that is required.

I should have mentioned compressor is not functioning, due to low refrigerant. I guess I hoped that I should be able to get ambient temperature vent air, without compressor, it always seems warmer than outdoor air.

I'm pretty sure compressor has slow leak, I see a drop or two of flourescent green oil on bottom side, near pulley, I think it's time to replace compressor again: I did replace compressor, TXV, drier, o rings about 10 years ago, leak only developed recently. I normally buy all AC parts from Arizona Mobile Air, but am open to other source of quality components. Thanks for the assistance.

No consult for the HVAC
we are asking for the refrigerant pressures, but that is irrelevant if the compressor does not engage.
have you converted to R-134a?

The self test is all done with the dash controller. It should tell you if there's a mix door problem.

I did recharge w R134A, at the time that I did replace compressor, TXV, drier, o rings, and flush about 10 years ago, leak only developed recently.

It cooled reasonably well, though not frosty like systems designed for R134A.

Has anyone had good cooling in Q45 designed for R12 that is converted to R134A?

Does anyone recommend a source for AC parts? I normally buy all AC parts from Arizona Mobile Air, but am open to other source of quality components. Thanks for the assistance.

If you've converted to 134a, I'd toss in a can or two and see how long it takes to leak down. Biggest loss is $5 for a can of it at Walmart. Be sure to get the new style of can tap. The feds mandated self sealing cans sometime last year. I think a new tap is about $10 at parts stores.

I did not know about new style can taps - looks like it screws onto threaded nipple at top of can. Previously I used the style that punches into the side of a can.

First to check the pressures, if it's down to nothing, I think I'll find the leak. IIRC it takes MOL 6 months to lose charge, that's a little frequent.

Big question is, I see new compressors for $400, to fit the old Q, looks like a made in China new compressor design. Reman'd are available at my usual source for $225. Has anyone installed one of the new? I'm tempted to try it, if my leak is the compressor, as I suspect, being as this would be my second replacement.

If any one else has retrofitted 90-93 with R134A I'm interested to know how well it cooled. The only alternative to R134A that I know of is propane, which I think cools really well. There's just a little flammability issue though... I would not recommend it.

This is the one I'm considering, AFAIK, it's the only new compressor available:
https://www.buyautoparts.com/buynow/199 ... 0-87719_R4

Has anyone else tried one?

Thanks.

This is the one I'm considering, AFAIK, it's the only new compressor available:
https://www.buyautoparts.com/buynow/199 ... 0-87719_R4

Has anyone else tried one?

Thanks.

Looks like no one has tried new compressor.

So yesterday I ran the self diagnostics, and 32 through 36 presented, sort of says the door motor does not run, and fits symptoms of no selection of ventilation outlet. Is anyone familiar with the door motor? Is it permanent magnet with brushes (typical servo motor, runs in either direction depending on polarity) or is it a stepper?

Also, unfortunately I snapped off the lever on my sunroof slide switch, had to jump the connector to close it. I have not looked, but something tells me replacements are not to be had, at least not new ones.

Thanks!

Not a ton of info on them, but I found this.

1991-q45-air-mix-door-motor-help-t619183.html

Thanks Heath. Next chance I get I'll check the door motors, I have a feeling that's the source of my warm air, well that and the lack of refrigerant. FSM documents the expected response of the door motors well enough.

Yesterday I replaced the snapped off sun roof switch with a couple of DPDT center neutral rocker switches (electric window up/down style), that worked out well, except I had to orient them such that the action is side to side, instead of inline with the car, they just wouldn't fit in the original recess otherwise.

Not having AC makes the sun roof control more necessary while commuting in Texas in the summer - I guess I should have fixed the AC last winter ...!